Self-propelled vehicle, in particular a road-building machine and a method for driving and controlling a vehicle with the aid of a rotatable driver seat
The invention refers to a self-propelled vehicle.
Such vehicles that have a rotatable driver's seat are known, for example, from road-building machines and in particular from road rollers.
It is a requirement with road rollers to develop a driver's seat that is freely rotatable around its vertical axis, since the operational conditions of a roller require a continuous change of the seat position of the operator relative to the travelling direction of the road roller. A prerequisite for a feasibility in terms of costs and functionality is that the control elements rotate with the driver's seat. Otherwise, a plurality of redundant control elements would have to be used, which would be expensive. Typically, an asphalt roller, for example, works behind a paver that places the material and performs a pre-compaction. The roller travels several times over the surfaces laid by the paver to provide the final compacting and the planarity of the surface. In doing so, the direction of travel is changed frequently—the number of forward and backward travels is almost equal. To provide for or improve upon the visibility of the working area, the security and the ergonomics of the operation of the machine, it is necessary to rotate the driver's seat by 180° every time the direction of travel is changed. Here, the roller may cab still on the hot asphalt only for the short duration taken by the change of the travelling direction. Therefore and for reasons of time, the driver's seat should be rotated while driving. For respective short distances with different travelling directions, a seat position rotated by 90° relative to the travelling direction is feasible. Depending on the course to be travelled, seat positions between 0 and 90° relative to the travelling direction may also be ergonomically feasible.
For a safe operation of the machines, the essential control elements, such as travelling direction transmitters (steering wheel, joystick) and drive lever, for selecting the travelling direction and the speed must be associated with the travelling direction in a manner unambiguous to the operator. Existing systems do not solve this problem. Accordingly, a free rotation of the driver's seat including the control elements while the roller travels—which is feasible in terms of application technology—was hereinbefore impossible.
EP 0935025 describes a system with a rotatable driver's seat, wherein the traction drive is controlled dependent on the rotational position of the driver's seat such that a control device reverses the direction of the drive presettings when the driver's seat is swivelled into a preset region. However, this reversal can only be effected with the roller at cabstill. Would the roller be travelling, rotating the driver's seat could for instance cause a reversal of the travelling direction of the roller that might not be intended by the driver.
From EP 0935023 A2, a method for a roller with two steerable drums that comprises a control device controlling the steering drive of both drums such that the respective front drum, seen in the travelling direction, is automatically controlled as the active drum through the steering presettings. Again, this method does not solve the problem of the sense of direction of the control elements when the seat position changes during travel.